Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by pronounced inflammation that affects up to 1.5 million persons in the US (1). While excess mortality has decreased in patients with SLE since the 1970s (2), a major ongoing cause of morbidity is chronic, debilitating fatigue (3) that significanty decreases quality of life (4-6), and increases risk of work disability (7) and associated health care costs (8). Thus, fatigue is a frequent and pervasive problem with adverse consequences for patients with SLE for which there are limited treatment options. An urgent, unmet need in the management of patients with SLE is identification of effective strategies to decrease fatigue (1). We focus on physical activity and dietary intake as potential lifestyle modifiable behaviors to help control weight and reduce fatigue in patients with SLE and we propose an intensive behavioral counseling program modeled after the successful Diabetes Prevention Program (9) to evaluate the effect of changes in physical activity and diet on fatigue in patients with SLE. To address this management gap for patients with lupus, we propose a planning grant for the Activity and Nutrition Trial in Lupus to Energize and Renew, ANTLER. A future application will request funding for the proposed clinical trial pending a successful planning phase. The current U34 application will support the development of a proposed clinical trial, ANTLER leveraging preliminary data from our ongoing NIAMS funded R21s, R21 AR059989 (Activity in Lupus to Energize and Renew, ALTER) and 1 R21 AR062317 (JointADventure: A Worksite Activity-Diet Intervention for Chronic Knee Pain), an NINR funded K23 NR012225 (Motivational Interviewing and Physical Activity Behavior Change in Arthritis), an NIDDK funded RC1DK087126, E-Networks Guiding Adherence to Goals for Exercise and Diet (ENGAGED), and an NHLBI funded R01HL076451 (Make Better Choices Study 2, MBC2). The specific aims for this U34 application include: 1) develop study protocol for U01 proposed clinical trial, ANTLER, 2) revise JointADventure intervention for ANTLER intervention arm, 3) develop educational modules for ANTLER control arm, 4), prepare U01 application for ANTLER, 5) develop manual of operations (MOP), forms and data systems, smartphone application, and training materials for ANTLER, and 6) prepare Human Subjects Protection Documents and Develop Data Safety Monitoring Plan for ANTLER. The preliminary specific aims for the future U01 clinical trial (ANTLER) application include: 1. Test the effectiveness of the ANTLER intervention for SLE to decrease fatigue, the primary outcome, and 2. Test the effectiveness of the ANTLER intervention for SLE to change physical activity and diet behavior, the secondary outcomes.